Simon Brown will eat toast and honey for breakfast tomorrow, pull on his well-worn sports shoes, nip down the road from his home in Devonport - then run and run and run.

Brown went for a gentle run yesterday morning in the last leg of his nearly five-month campaign of preparations for tomorrow's adidas Auckland Marathon. It will be his first marathon.

The 42.195km race starts in Devonport at 6.10am, takes in the Harbour Bridge and the Auckland city waterfront out to St Heliers and back to the finish line at Victoria Park.

Brown, a 38-year-old HR manager and married father of one, hopes to complete the run in a little over four hours, but achieving a particular time is not his main aim.

"I feel reasonably confident that, barring injuries, I will be able to run it. For me, being the first time, it's more about finishing a race."

He has had "niggling" injuries in a knee and a hamstring which caused some troubles in his gradual build-up of training. But after physiotherapy and help with changing his running style and some strength training, he believes they are under control.

Brown says he has always been reasonably fit, playing football and doing "a little bit of moderate running" at times. But in his marathon training the runs have become more frequent, with some long stints at weekends.

"The most I've run would be 32km," he says.

"I used to get really bored running and I didn't expect to like the training, but I've really quite enjoyed it. I find you hit a certain stage where you get into that flow, your mind kind of wanders. It's quite a nice sensation. You can think with a bit of clarity. The most I've run is about three hours - the time just goes by."

"The downside is the time it takes. I try to go first thing in the morning."

Sports physician Dr Mark Fulcher urges entrants to focus on enjoying the run rather than trying to achieve a particular time - "go slower than you think you should".

Keep an eye on the forecast - last night it was for rain, showers and a maximum of 20C - and if it's cold, wear extra layers; if hot, go slower and drink more.

"Try to consume some carb (from the supplied sports drinks) while out there, particularly if you think you're going to be on the course for a long time."

It's a marathon morning

The full and half marathon start early tomorrow morning in Devonport.

More than 16,000 people have signed up to run - or walk - in tomorrow's Auckland Marathon.

There are five events: the full marathon (42.195km), half, quarter, 5km challenge - and the children's marathon, which runs the full marathon distance but in multiple legs spread over a number of weeks with only the final 2.195km being staged tomorrow.

The full marathon and the half start in King Edward Parade, Devonport, at 6.10am and 7am respectively. The quarter starts in Gaunt St, central Auckland, at 6.45am and the 5km event in Sarsfield St, Herne Bay, at 9.45am.

At the competitive end of the longer runs, New Zealanders are expected to face tough competition from across the Ditch.

Athletics NZ says an "Australian double is on the cards", with Rowan Walker in the men's marathon and Anita Keem the favourite for the women's.

But Walker will be challenged by Aucklander Scott Winton and Cantabrian Dave Ridley. Walker won the Australian marathon championship in 2010 with a personal best of just over two hours and 18 minutes, when he came third in the Melbourne marathon but was first Aussie over the line.

The adidas Auckland Marathon doubles as the New Zealand marathon national championships.